Large magnetic entropy change near room temperature in La0.7(Ca0.27Ag0.03)MnO3 perovskite

In this paper, the magnetic properties and magnetocaloric effect (MCE) of La-0.7(Ca1-xAgx)(0.3)MnO3 (x=0, 0.1, 0.2, 0.7, and 1) powder samples are reported. Our polycrystalline compounds were synthesized using the solid state reaction method at high temperature. Magnetization measurements versus temperature showed that all our samples exhibited a paramagnetic to ferromagnetic transition with decreasing temperature. The Curie temperature, T-C, has been found to increase from similar to 250K for x = 0-270 K for x = 1. Ag doping weakens the first order phase transition, and at higher Ag doping, the phase transition is of second order. For the La-0.7(Ca0.27Ag0.03)MnO3 composition, the maxima of the magnetic entropy changes from the applied magnetic field (Delta S-M) at 2 and 5T are about 4.5 and 7.75 J/kg K, respectively, at the Curie temperature of similar to 263 K. The relative cooling power (RCP) values without hysteresis loss are about 102 and 271 J/kg for the applied fields of 2 and 51, respectively. Due to the large Delta S-M, large RCP, and high Curie temperature, La-0.7(Ca0.27Ag0.03)MnO3 is promising for application in potential magnetic refrigeration near room temperature. (C) 2010 Elsevier B.V. All rights reserved.